Impact of Neighborhood Disadvantage on Tumor Biology and Breast Cancer Survival

Objective: The aim of this study was to evaluate the association between neighborhood disadvantage and Oncotype DX score, a surrogate for tumor biology, among a national cohort. Background: Women living in disadvantaged neighborhoods have shorter breast cancer (BC) survival, even after accounting for individual-level, tumor, and treatment characteristics. This suggests unaccounted social and biological mechanisms by which neighborhood disadvantage may impact BC survival. Methods: This cross-sectional study included stage I and II, ER⁺/HER2^-BC patients with Oncotype DX score data from the National Cancer Database (NCDB) from 2004 to 2019. Multivariate regression models tested the association of neighborhood-level income on Oncotype DX score controlling for age, race/ethnicity, insurance, clinical stage, and education. Cox regression assessed overall survival. Results: Of the 294,283 total BC patients selected, the majority were non-Hispanic White (n=237,197, 80.6%) with 7.6% non-Hispanic Black (n=22,495) and 4.5% other (n=13,383). 27.1% (n=797,254) of the population lived in the disadvantaged neighborhoods with an annual neighborhood-level income of <$48,000, while 59.62% (n=175,305) lived in advantaged neighborhoods with a neighborhood-level income of >$48,000. On multivariable analysis controlling for age, race/ethnicity, insurance status, neighborhood-level education, and pathologic stage, patients in disadvantaged neighborhoods had greater odds of high-risk versus low-risk Oncotype DX scores compared with those in advantaged neighborhoods [odds ratio=1.04 (1.01-1.07), P=0.0067]. Conclusion and Relevance: This study takes a translational epidemiologic approach to identify that women living in the most disadvantaged neighborhoods have more aggressive tumor biology, as determined by the Oncotype DX score.